Use of a magnetic material in removal of stones

ABSTRACT

The invention relates to a method of a magnetic material in stone removal, nanoparticles, a preparation method thereof and a stone removing device. Wherein, the magnetic material constitutes a nanoparticle core and a surface modifier monomer is attached to the nanoparticle core by an initiator and/or a crosslinking agent to form a nanoparticle shell. The prepared nanoparticles can surround stones in ureter, thereby, small stones remaining in body can be removed quickly without damage from the body under action of external magnetic field, that is, the stone can be drawn and moved without injuring ureteral wall, and the nanoparticles are placed conveniently without shift.

TECHNICAL FIELD

The present invention relates to a use of a magnetic material in removalof stones, nano-particles, a method for preparing the same, includes adevice comprising nano-particles for removal of stones.

BACKGROUND ART

Urinary calculi/stone (urolithiasis) have an incidence as high as 5%-10%, and can be found in any part of kidney, bladder, ureter andurethra, in which stones in kidney and ureter are common. It is found inclinical observation that calcium-containing stones are the most commontypes of urinary stones, that is, about 70% to 80% of all urinarystones. At present, there are only a few cases of calcium-containingstones which pathological causes have been clearly revealed, while thecauses for most of calcium-containing stones are not yet clear.According to chemical composition, stones can be divided into fourcategories: calcium-containing stones, infection induced stones, uricacid stones and cystine stones. Calcium-containing stones can be dividedinto following types: simple calcium oxalate, calcium oxalate withcalcium phosphate, calcium oxalate with a small amount of uric acid; themain components of infection induced stones are ammonium magnesiumphosphate and hydroxyapatite; uric acid stones can be divided intofollowing types: uric acid, uric acid amine, or those containing a smallamount of calcium oxalate in addition to the above ingredients; cystinestones can be divided into following types: simple cystine, or cystinewith a small amount of calcium oxalate.

Soft/hard ureteroscopic lithotripsy is performed through natural channelof the human body, has the advantages of small trauma and definitelithothriptic effect, and is currently the main treatment means for mostof ureteral stones and kidney stones. However, the current soft/hardureteroscopic lithotripsy also has some deficiencies: 1) upper ureteralstones and fragments of stones in ureter may be easily brought back tokidney by the infused water or the recoil force of lithotripsy tools; 2)there is lack of a fast, safe and effective method to take out residualdebris of stones in ureteral lumen and kidney calices. It is animportant mean to prevent ureteral stones from being recoiled back tokidney that a tool is used to block the ureter above the ureteralstones. At present, there are also some ureteral occluders in clinicalpractice, and such kind of stones blocking tools are also commonly usedto remove stones. However, these ureteral occluders still have someshortcomings in actual use. Stone baskets (such as various stone basketsdescribed in Patent Publication No. JP2009536081A, DE19904569A1,WO2004056275A1, WO2011123274A1 are designed with a net bag) are the mostcommonly used stone interception and removal tools, which cross overstone and then are opened to form a net so as to prevent the upwarddrift of stone debris, and at the same time, the stone baskets are alsoused as stone removal tools to net and take out small stone debris.However, the amount of stone removed by the stone basket every time islimited, so that multiple feeds of ureteroscope are needed, whilerepeated injection of water and feeds of ureteroscope would increase therisk of residual debris drift; in addition, the stone basket cannotcompletely seal the ureteral lumen, and there are still a chance thatstones escape from the net; moreover, the edges of stones in stonebasket may be easily squeezed out from basket holes, and thus may easilyscratch the ureter wall when the stones are dragged and removed, therebycausing complications in severe cases.

In addition, CN105283140A describes a kit of a cross-linked gel forencapsulating urethral stones and/or debris of urethral stones. However,when a gel-containing magnetic reagent (mock) is added to an aqueoussolution containing stones, the cationic polymer is dispersedsubstantially in the form of dissolving in a solvent rather thanaggregates to the periphery of stones due to the principle of similarcompatibility, which is not sufficient to magnetize stones and removestones.

In summary, there is an urgent need for a material and method forremoval of stone in urinary system that can collect stones, facilitatethe stone taking, do not damage the ureteral wall when the stones aredragged, can be conveniently placed and are not easy to cause shift ofstone.

CONTENTS OF THE INVENTION

The present invention is aimed to solve the problem of residual stonedebris and difficult removal thereof in the conventional soft/hardureteroscopic lithotripsy. Therefore, a first object of the presentinvention is to provide a use of a magnetic material in removal ofstones; a second object of the present invention is to provide amagnetic material capable of safely and efficiently removing urinarystones located in the kidney, ureter, etc., wherein the magneticmaterial is a magnetic nano-material; a third object of the presentinvention is to provide a method for preparing the magnetic material indifferent morphological structures, wherein the magnetic material is amagnetic nano-material; a fourth object of the present invention is toprovide a use of the magnetic material in combination with a self-mademagnetic probe rod system in a urinary stones surgery, wherein themagnetic material is a magnetic nano-material; a fifth object of thepresent invention is to provide a use of the magnetic material inmanufacture of an article for removal of stones in urinary system,wherein the magnetic material is a magnetic nano-material.

A first aspect of the present invention provides a solution 1, that is,a use of a magnetic material in removal of stones, wherein the magneticmaterial magnetizes the stones by physical adsorption, chemical bondingor the like, and removes the stones by the action of a non-contactmagnetic field.

2. The use according to the embodiment 1, wherein the magnetic materialcomprises the following components: a preparation containing a magneticmetal element or a compound thereof; and materials capable of binding tocalcium salt.

3. The use according to the embodiment 2, wherein the preparationcontaining the magnetic metal element or compound thereof and thematerial capable of binding to calcium salt form a structure that may bea clad structure or a core-shell structure, for example, the materialsare completely or partially coated on the surface of the preparation; orform a modified structure in which the materials are bonded to thesurface of the preparation by absorption; or form a complex structure inwhich the preparation and the materials form a physical mixture; or forma composite structure of the aforementioned structures.

4. The use according to the embodiment 2, wherein the preparationcontaining the magnetic metal element or compound thereof is innano-scale or in micro-scale.

5. The use according to the embodiment 2, wherein the materials capableof binding to calcium salt are surfactant or polymer compounds.

6. The use according to embodiment 2, wherein the materials capable ofbinding to calcium salt are macromolecular compounds.

7. The use according to the embodiment 1, wherein the magnetic materialincludes carboxyl, amido, amino, mercapto, hydroxyl, carbonyl, ethergroup, amine group, ester group, carbamate group, carbamido orquaternary amine group, sulfonic acid group, sulfhydryl, phosphine groupor conjugate acid or base thereof, epoxy group, chlorine group, sulfategroup, phosphinic acid, sulfinic acid, carboxylic anhydride group,hydrosilyl group, amine group and moiety of any combination thereof,aldehyde group, unsaturated double bond, phosphoric acid group, halogengroup, N-succinimido, maleimido, ethylenediaminetriacetic acid alkylgroup, polyethylene glycol, polyamino acid or glycan, preferablycarboxyl, amido, mercapto, carbamate group, carbamido, sulfonic acidgroup, phosphino conjugate acid, phosphino basic group, sulfate group,phosphinic acid, sulfinic acid, N-succinimido, maleimido, polyaminoacid.

8. The use according to the embodiment 1, wherein the magnetic materialis in the shape of bar, line, band, sheet, tube, pomegranate, cube,three-dimensional flower, petal, chestnut, four-pointed star, shuttle,rice grain, sea urchin, chain ball, rugby ball, string of beads,snowflake, ellipsoid, sphere, regular tetrahedron, regular hexahedron,regular octahedron, quasi-sphere, popcorn, cross, strip, rod, cone,disc, branch, web, simple cubic, body-centered cubic, face-centeredcubic, simple tetragon, body-centered tetragon, simple orthogonbody-centered orthogon, single-face-centered orthogon, multi-shell,laminar, preferably the shape of sphere, quasi-sphere, pomegranate,chestnut, sea urchin, chain ball, string of beads.

9. The use according to the embodiment 1, wherein the magnetic materialincludes a magnetic fluid, a magnetic liposome, a magnetic microcapsule,a magnetic microsphere, a magnetic emulsion, a magnetic nanoparticle, amagnetic nanotube, a magnetic nanowire, a magnetic nanorod, a magneticnanoribbons, preferably a magnetic fluid, a magnetic liposome, amagnetic microsphere, a magnetic nanotube.

10. The use according to the embodiment 9, wherein the magnetic liposomeincludes a magnetic liposome which surface is modified to carry afunctional group as described in the embodiment 7.

11. The use according to the embodiment 9, wherein the type of themagnetic liposome includes a single layer, a multi-layer, amulti-vesicle, and the preparation method of the magnetic liposomeincludes preferably a film dispersion method and an ultrasonicdispersion method.

12. The use according to the embodiment 9, wherein the magnetic fluid isa stable suspension liquid composed of magnetic particles, a carrierliquid (mineral oil, silicone oil, etc.) and a surfactant, the magneticparticles that can be used for removal of stones comprise magneticnanoparticles which surface is modified with the functional groupaccording to the embodiment 7, and also comprise a surfactant with thefunctional group as described in the embodiment 7.

13. The use according to the embodiment 9, wherein the preparationmethod for the magnetic fluid includes a chemical co-precipitationmethod, a sol-gel method, a hydrothermal synthesis method, amicroemulsion method, a phase transfer method, preferably aco-precipitation method, a sol-gel method, a hydrothermal synthesismethod.

14. The use according to the embodiment 9, wherein the magneticmicrosphere is characterized by a surface modified with the functionalgroup as described in the embodiment 7.

15. The use according to the embodiment 9, wherein the preparationmethod for the magnetic microsphere includes an emulsion volatilizationmethod, a solvent replacement method and a salting-out method.

16. The use according to the embodiment 1, the magnetic nanotubecomprises a magnetic nanotube in which a magnetic material is filled inthe tube and also a magnetic nanotube in which a magnetic materialcovers outside the tube, the surface of which has the functional groupdescribed in the embodiment 7, and the functional group may be derivedfrom the magnetic material covered on surface or from the nanotubeitself.

17. The use according to the embodiment 1, wherein the preparationmethod for the magnetic nanotube includes a chemical vapor depositionmethod, a co-precipitation method, a dip-pyrolysis method, anelectroless plating method and a self-assembly method, and the preferredmethod is a co-precipitation method.

18. The use according to the embodiment 1, the magnetic nanoparticle issurface-modified or covered with the functional group as described inthe embodiment 7.

19. The use according to the embodiment 1, wherein the magnetic materialconstitutes a nanoparticle core; and the nanoparticle core is modifiedin-situ with a surface modifier monomer by using an initiator and/or acrosslinking agent to form a nanoparticle shell.

20. The use according to the embodiment 19, wherein the nanoparticlecore has a diameter of 2-50 nm, and a weight percentage of 30-95%relative to the whole weight of the nanoparticle, and its magneticmaterial includes a compound of Fe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, or a metalelement selected from iron, nickel, copper, cobalt, platinum, gold,europium, gadolinium, dysprosium, terbium, or a composite or oxide ofthe aforementioned metals, or any one of the above items or acombination of two or more of the above items, preferably a compound ofFe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, more preferably Fe³⁺ and Fe²⁺ in a ratio of15% to 85%, preferably 1:2.5 to 1.5:1.

21. The use according to the embodiment 19, wherein the mutual forcesfor surrounding and crosslinking between the nanoparticle and stoneinclude van der Waals force, hydrophobic interaction, adsorption andsurface deposition that form surrounding interactions; a chemical bondformed between carboxyl-stone, including a hydrogen bond, an ester bond,an amide bond and other covalent bonds; physical and chemicalinter-chain entanglements between chains and chemical crosslinkingbetween chains.

22. The use according to any one of the embodiments 19-22, wherein thesurface modifier includes a hydrophilic surface modifier with functionresponse, a hydrophobic surface modifier with function response, aphotosensitive surface modifier with function response, athermosensitive surface modifier with function response or a pHsensitive surface modifier with function response, wherein thehydrophilic surface modifier includes acrylic acid, methacrylic acid,isobutyl acrylamide or poly N-substituted isopropylacrylamide; thehydrophobic surface modifier includes olefins, preferably polystyrene,polyethylene or oleic acid; the photosensitive surface modifier isselected from the group consisting of azos and quinolines andbenzophenones (PVBP), preferably ethylene benzophenone; thethermosensitive surface modifier is selected from the group consistingof amphiphilic polymers with amide bond, preferably polyacrylamide orpoly N-substituted isopropylacrylamide; the pH-sensitive surfacemodifier is selected from the group consisting of polymers with carboxylgroup and quaternary ammonium salt, preferably a polyacrylic acid,dimethylaminoethyl ester and dimethylaminopropyl methacrylate; the shellaccounts for 2-40% by weight of the nano-particle, preferably theparticle is of a shape of sphere, rod or diamond.

23. The use according to any one of the embodiments 19 to 22, whereinthe crosslinking agent includes3-(methacryloyloxy)propyltriethoxysilane, divinylbenzene, diisocyanateor N,N-methylenebisacrylamide, and the initiator includes3-chloropropionic acid, CuCl, 4,4′-dinonyl-2,2-bipyridine or potassiumpersulfate.

24. The use according to any one of the embodiments 19-22, wherein thepreparation method for the nanoparticle includes the steps of:

a) preparation of the nanoparticle core using the magnetic material;

b) forming the nanoparticle by in situ linking the surface modifiermonomer to the nanoparticle core by the initiator and/or crosslinkingagent to form the nanoparticle shell.

25. The use according to the embodiment 24, wherein the magneticmaterial includes a compound of Fe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, or a metalelement selected from iron, nickel, copper, cobalt, platinum, gold,europium, gadolinium, dysprosium, terbium, or a composite or oxide ofthe aforementioned metals, or any one of the above items or acombination of two or more of the above items, preferably Fe₃O₄,MnFe₂O₄, γ-Fe₂O₃ or other nanoscale-sized ferrite particles, morepreferably FeCl₃.6H₂O and FeCl₂.4H₂O in a molar ratio of 15% to 85%,preferably 1:2.5 to 1.5:1, and is prepared by the following steps:

dissolving a proportion of the metal salt-containing material in water;

feeding nitrogen to expel oxygen in the solution;

adding a catalyst at a room temperature of 10-40° C., preferably 30° C.to adjust the pH to 7-12, preferably 10;

keeping agitation for 10-60 minutes; and

reacting under condition of 40-100° C., preferably 70° C. water bath,for 20-40 minutes, then separating with a magnet and drying to obtainthe magnetic nanoparticle core.

26. The use according to the embodiment 25, wherein when aqueous ammoniais used as the catalyst for preparing the nanoparticle, the method foradding aqueous ammonia is a continuous dropping method with assistanceof an electronic pump at a speed of 20-100 drops/minute, preferably40-60 drops/minute; and when the magnetic material is a liquid monomermaterial, the liquid monomer is added dropwise in continuous manner withassistance of an electronic pump, and the reaction agitation is at aspeed of 100-1000 revolutions/minute, preferably 500-700revolutions/minute.

27. The use according to any one of the embodiments 24-27, wherein saiduse further includes performing hydrophobic surface modification on theobtained nanoparticle core, comprising the steps of:

dispersing the prepared nanoparticle core in an aqueous solution andadded with a xylene solution of 3-chloropropionic acid, polystyrene,CuCl and 4,4′-dinonyl-2,2-dipyridine, and the molar ration between theabove-mentioned nanoparticle core and the reaction solution is 1:1;

reacting the above mixture at 130° C. with continuous agitation for15-30 h, preferably for 24 hours; and

collecting the nanoparticle with a magnet and washing repeatedly withtoluene to obtain a hydrophobic polystyrene-coated magneticnanoparticle.

28. The use according to any one of the embodiments 24-27, wherein saiduse further includes performing hydrophilic surface modification on theobtained nanoparticle core comprising the steps of:

dispersing the nanoparticle core in xylene, and adding a silane couplingagent, wherein the ratio of the added nanoparticles, xylene and silanecoupling agent is 95:5;

reacting under protection of nitrogen atmosphere at a temperature of 20to 100° C., preferably 80° C. for 2 to 5 hours, preferably 3 hours;

washing with an alcohol solvent and drying for 12 h, dispersing in anaqueous solution under ultrasonic condition, adding with potassiumpersulfate;

reacting under protection of nitrogen atmosphere at 40-80° C. for 10minutes, then adding with acrylic acid and continuously reacting at40-80° C. for 1 hour, preferably reacting at 70° C.; and

separating by a magnet, washing and drying to prepare and obtain apolyacrylic acid-modified hydrophilic nanoparticle.

29. The use according to any one of the embodiments 24-27, wherein saiduse further includes performing a photosensitive, thermosensitive orpH-sensitive surface modification based on the resulting nanoparticlecore or hydrophilic surface, or a hydrophilic, hydrophobic,photosensitive, thermosensitive and pH-sensitive co-modification basedon the resulting nanoparticle core, wherein the re-modification on thehydrophilic surface includes the steps of:

dissolving and dispersing the polyacrylic acid-modified magneticnanoparticles in an alcoholic solvent, adding with a photosensitivemonomer such as ethylene benzophenone, a thermosensitive monomer such asN-isopropylacrylamide, or a pH-sensitive monomer such asdimethylaminopropyl methacrylate or a blend monomer of acrylic acid andstyrene, keeping reaction at 40-80° C. for 1 h, preferably at a reactiontemperature of 70° C.; and separating with a magnet, washing and dryingto obtain a photosensitive, thermosensitive or pH sensitive functionalmonomer-modified magnetic nanoparticles, respectively.

30. The use according to the embodiment 1, wherein the stone compriseurinary system stones, such as kidney stones, ureteral stones andbladder stones, human biliary system stones, and stone-like particles inother organs.

31. The use according to the embodiment 1, wherein the interactionsbetween the magnetic material and stone include ionic bonds, van derWaals forces that form surrounding interactions, hydrophobicinteractions, adsorption and surface deposition; chemical bonds betweenthe carboxyl-stone, including hydrogen bonds, ester bonds, amide bondsand other covalent bonds; physical and chemical inter-chain entanglementbetween chains and chemical crosslinking between chains.

A second aspect of the present invention provides a nanoparticlecomprising a nanoparticle core comprised of the magnetic material; and ananoparticle shell formed by linking a surface modifier monomer to thenanoparticle core via an initiator and/or a crosslinking agent.

According to some embodiments of the present invention, the nanoparticlesurrounds a stone via physical adsorption, chemical bonding, as well asphotosensitive crosslinking, thermosensitive crosslinking andpH-sensitive crosslinking, specifically, the forces for binding andsurrounding interactions between the nanoparticle and stone include: vander Waals forces that form surrounding interactions, hydrophobicinteractions, adsorption and surface deposition; covalent bonds formedbetween carboxyl-stone, including hydrogen bonds, ester bonds, amidebonds, and other covalent bonds; physical entanglement and chemicalcrosslinking between chains.

According to some embodiments of the present invention, the nanoparticlecore has a diameter of 2-50 nm, and a weight percentage of 30-95%relative to the whole weight of the nanoparticle, and the magneticmaterial constituting the core includes a compound of Fe³⁺, Fe²⁺, Mn²⁺or Ni²⁺, or a metal element selected from iron, nickel, copper, cobalt,platinum, gold, europium, gadolinium, dysprosium, terbium, or acomposite or oxide of the aforementioned metals, or any one of the aboveitems or a combination of two or more of the above items, preferably oneor a combination of two or more of Fe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, morepreferably Fe³⁺ and Fe²⁺ in a ratio of 15% to 85%, preferably 1:2.5 to1.5:1. It should be noted that the preparation method of thenanoparticle used in the present invention can well control the size ofthe magnetic nanoparticle core, especially in comparison with thenanoparticles prepared by other methods, among the parameters of thenanoparticles obtained in the present invention, the dispersibility ofnanoparticles relative to biomedical applications is very good and lessthan 1.1.

According to certain embodiments of the present invention, the surfacemodifier includes a hydrophilic surface modifier with function response,a hydrophobic surface modifier with function response, a photosensitivesurface modifier with function response, a thermosensitive surfacemodifier with function response or a pH sensitive surface modifier withfunction response, wherein the hydrophilic surface modifier includesacrylic acid, methacrylic acid, isobutyl acrylamide or polyN-substituted isopropylacrylamide; the hydrophobic surface modifierincludes olefins, preferably polystyrene, polyethylene or oleic acid;the photosensitive surface modifier is selected from the groupconsisting of azos and quinolines and benzophenones (PVBP), preferablyethylene benzophenone: the thermosensitive surface modifier is selectedfrom amphiphilic polymers with amide bond, preferably polyacrylamide orpoly N-substituted isopropylacrylamide; the pH-sensitive surfacemodifier is selected from the group consisting of polymers with carboxylgroup and quaternary ammonium salt, preferably a polyacrylic acid,dimethylaminoethyl ester and dimethylaminopropyl methacrylate.

According to some embodiments of the present invention, the crosslinkingagent includes 3-(methacryloyloxy)propyltriethoxysilane, divinylbenzene,diisocyanate or N,N-methylenebisamide, and the initiator includes3-chloropropionic acid, CuCl, 4,4′-dinonyl-2,2-bipyridine or potassiumpersulfate.

The third aspect of the invention provides a method of preparing thenanoparticle, comprising the steps of: a) preparing the nanoparticlecore using the magnetic material; and b) forming the nanoparticle shellby in situ linking the surface modifier monomer to the nanoparticle coreby the initiator and/or crosslinking agent to form a nanoparticle shell.As used herein, “in situ” means that the surface modifier is directlyattached to the surface of the nanoparticle core. The resulting modifiednanoparticle has a size between 50 nm and 5000 nm, which variesaccording to different conditions.

According to some embodiments of the present invention, the nanoparticlecore is composed of Fe₃O₄, MnFe₂O₄, γ-Fe₂O₃, or other nanoscale-sizedferrite particles, and these ferrite particles are prepared by thefollowing steps:

dissolving a proportion of the metal salt-containing material in water;

feeding nitrogen to expel oxygen in the solution;

adding a catalyst at a room temperature of 20-30° C. to adjust the pH to8-12, preferably 10;

keeping agitation and reaction for 20-40 minutes; and

reacting under condition of 50-100° C., preferably 70° C. water bath,for 20-40 minutes, then separating with a magnet and drying to obtainthe magnetic nanoparticle core.

In a particular embodiment of the present invention, theoxygen-containing metal salt is FeCl₃.6H₂O and FeCl₂.4H₂O, which aredissolved in water in a molar ratio of 15% to 85%, preferably 1:2.5 to1.5:1, wherein the catalyst is ammonia. Fe₃O₄ nanoparticles can beobtained by following the above steps.

According to some embodiments of the present invention, the step b)includes dispersing the prepared nanoparticles in an aqueous solution,adding with an xylene solution of 3-chloropropionic acid, polystyrene,CuCl and 4,4′-dinonyl-2,2-bipyridine, wherein the molar ratio betweenthe solution of iron particles and the reaction solution is 1:1;reacting the mixture for 15-30 hours, preferably 24 hours, at 130° C.under continuous agitation; and collecting the nanoparticles with amagnet, washing with repeatedly with toluene to obtain hydrophobicpolystyrene-coated magnetic iron oxide nanoparticles.

According to some embodiments of the present invention, the step b)includes dissolving and dispersing the resulting nanoparticle core intoxylene, adding with a silane coupling agent, wherein the silane couplingagent, wherein the nanoparticles, xylene and silane coupling agent areadded in a ratio of 95:5; reacting under the protection of nitrogenatmosphere at 20-100° C., preferably at 80° C., for 2-5 hours,preferably for 3 hours; washing with an alcoholic solvent (preferablyabsolute ethanol) and drying for 12 hours, dispersing in an aqueoussolution under ultrasonic condition, adding with potassium persulfate;reacting under nitrogen protection, 40-80° C. for 10 minutes, addingwith acrylic acid to continue reaction at 40-80° C. for 1 hour, whereinthe reaction temperature is preferably 70° C.; and separating with amagnet, washing and drying to obtain the polyacrylic acid-modifiedhydrophilic nanoparticles.

According to some embodiments of the present invention, the above step bincludes: dissolving and dispersing Fe₃O₄ nanoparticles into xylene, andadding with a silane coupling agent, wherein the silane coupling agent(the ratio of the added Fe₃O₄ nanoparticles and the silane couplingagent is 95:5); reacting under protection of nitrogen atmosphere at 80°C. for 2-5 hours, preferably for 3 hours; washing with an alcoholicsolvent (preferably absolute ethanol) and drying for 12 hours,dispersing in an aqueous solution under ultrasonic condition, addingwith potassium persulfate; reacting under nitrogen protection at 40-80°C. for 10 minutes, adding with a photosensitive monomer such as vinylbenzophenone, a thermosensitive monomer such as N-isopropylacrylamide,or a pH-sensitive monomer such as dimethylaminopropyl methacrylate, etc.(or a blended monomer of acrylic acid and styrene), reactingcontinuously for 1 hour at 40-80, preferably at 70; and separating witha magnet, washing and drying to obtain the photosensitive,thermosensitive or pH sensitive functional monomer-modified magneticnanoparticles, respectively.

In certain embodiments of the present invention, the photosensitivemonomer modification based on the hydrophilic surface modificationincludes: dissolving and dispersing the polyacrylic acid-modifiedmagnetic nanoparticles in an alcoholic solvent, dispersing for 5-30minutes under ultrasonic condition, then adding an initiator and aphotosensitive monomer polyvinylbenzophenone, refluxing and reacting atagitation and 130° C. for 24 hours under condition that oxygen is keptout to prepare the photosensitive monomer-modified magneticnanoparticles.

In the above embodiment, when aqueous ammonia is used as catalyst toprepare the nanoparticles, the method for dropping aqueous ammonia isperformed in a continuous and dropwise manner with assistance of anelectronic pump at a speed of 20-100 drops/minute, preferably 40-60drops/minute; and when the magnetic material is an element material, theliquid monomer is added in a dropwise and continuous manner withassistance of an electronic pump, and the reaction is carried out underagitation with a speed of 100-1000 revolutions/minute, preferably500-700 revolutions/minute.

It should be noted here that the particle size, distribution andmorphology (such as shape of sphere, rod, diamond, etc.) of the obtainedmagnetic nanoparticle core can be relatively easily controlled under thesynthetic methods and preparation conditions as we designed above.Furthermore, the surface-modified magnetic nanoparticles prepared by theabove method have particle size and distribution superior to those ofmagnetic nanoparticles obtained by conventional preparation methods. Asshown in the following table, the dispersibility index (PD.I.) of theobtained nanoparticles is basically close to 1.0, which clearly showsthat the particle size distribution of the obtained particles is narrow.This is very important because, for in vivo biomedical applications, thesize and dispersion of nanoparticles determine the breadth of theirmedical applications. The PD.I described herein for describing thedispersibility of nanoparticles is defined as follows:

PD.I.=<Rh ² >/<Rh> ²

wherein, Rh represents hydrodynamic radius of particle.

The nanoparticle core and the surface-modified magnetic nanoparticlehave distribution PD.I. as shown in the following table:

Magnetic nanoparticle core After surface modification Diameter/nm 40-5080-100 PD.I./a.u. 0.005 0.0055

In addition, as shown in FIG. 2, the structure of the nanoparticlesobtained in the present invention is clear.

According to a fourth aspect of the present invention, there is provideda device for removal of stone, which can be used in the urinary systemand consists of a magnetic nanoparticle in combination with astone-removal magnetic probe rod system. The device for removal of stonecomprises the above-mentioned nanoparticles of the present invention andan auxiliary stone-removal magnetic probe rod system. The device forremoval of stone can be used for removing a stone in urinary system suchas kidney stone, ureteral stone and bladder stone, etc., as well asremoving a stone in human biliary system and a stone-like particle inother organs.

Specifically, the stone-removal magnetic probe rod system comprises ahandle, a flexible rod, a magnetic field source, a magneticallypermeable material section, etc., in which the handle may be providedwith an AC or DC power supply, a power switch, a DC battery compartmentand an AC plug; the flexible rod is made of a polymer materialincluding, for example, PU, TPU, PE, PVC, NYLON, PEBAX and siliconerubber and the modified materials of the above materials, the magneticfield source made of a permanent magnet or electromagnet can be embeddedin the flexible rod, and optionally a high performance magneticallypermeable material is connected to the magnetic field source to form theflexible probe rod with different configurations, for example, thepermanent magnet is placed in the middle or back end of the flexiblerod, and the magnetically permeable material is placed in the distal endof the flexible rod, so that such configuration is more conducive to thetreatment of renal stones under ureteroscope to avoid the situation thatthe distal end of the flexible rod becomes rigid due to the rigidstructure of the permanent magnet or the electromagnet, so that suchmagnetic probe rod can be successfully inserted into the working channelof ureteroscope, and inserted into upper, middle and lower kidneycalices to carry out stone removal operation when driven by theureteroscope.

In a fifth aspect of the invention, there is provided a use of thenanoparticle of the present invention in manufacture of an article, inwhich the nanoparticle is prepared in the form of a solution or powder.

The invention provides a novel preparation process for synthesizinghydrophilic, hydrophobic, thermosensitive and pH-sensitive as well asphotosensitive magnetic nanoparticles, which has the advantages ofsimple preparation process, good repeatability and convenientapplication. By the hydrophobic interaction between the preparedhydrophobic nanoparticles and stones, the chemical bond interactionbetween hydrophilic nanoparticles and stones, and the polymerization ofthe photosensitive nanoparticles under illumination, the stones aresurrounded; and the thermosensitive and pH-sensitive nanoparticles cansurround stones through physically surrounding action in ureter;thereby, small stone remaining in body can be removed quickly withoutdamage from the body under the action of an externally applied magneticfield, that is, the stone can be drawn and moved without injuringureteral wall, and meanwhile the nanoparticles are placed convenientlywithout shift.

The present invention is further described with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the transmission electron microscope (TEM) images and theparticle size distribution diagrams under dynamic light scattering forthe cores with different morphologies obtained in Example 1 of thepresent invention.

FIG. 2 shows the particle size distribution diagram under dynamic lightscattering for the monomer-modified nanoparticles obtained in Example 4of the present invention; and TEM images of the monomer-modifiednanoparticles obtained in Example 3 of the present invention.

FIG. 3 shows the hysteresis curves of the monomer-modified nanoparticlecores with different Fe³⁺/Fe²⁺ ratios in the synthesis of thenanoparticles obtained in Example 3 of the present invention.

FIG. 4 shows the graphs of stone separation for the photosensitivemonomer-modified nanoparticle cores obtained in Example 4 of the presentinvention, and the graphs of separation performance for the nanoparticlecores synthesized with different Fe³⁺/Fe²⁺ ratios and modified withfunctional monomer.

FIG. 5 shows a graph of biocompatibilitv to 293t cells for thefunctional magnetic nanoparticles obtained in Example 4 of the presentinvention.

FIG. 6 shows a graph of stone separation with in vitro assistance forthe nanoparticles obtained in Example 6 of the present invention.

FIG. 7 shows a graph of safety evaluation in body of animals for thenanoparticles of the present invention.

FIG. 8 shows an overall schematic diagram of the magnetic probe rodsystem for assisting stone removal in the present invention.

FIG. 9 shows a schematic view of the handle portion of the magneticprobe rod system for assisting stone removal in the present invention.

FIG. 10 shows a schematic view of the magnetic probe rod system with anAC power supply for assisting stone removal according to the presentinvention.

FIG. 11 shows a schematic view of the internal structure of the magneticprobe rod system using an electromagnet as magnetic field sourceaccording to the present invention.

FIG. 12 shows a schematic view of the magnetic probe rod system of thepresent invention which uses an electromagnet as magnetic field sourceand a magnetically permeable material section at distal end.

FIG. 13 shows a schematic view of the magnetic probe rod system of thepresent invention which uses a permanent magnet as magnetic field sourceand a magnetically permeable material section at distal end.

FIG. 14 shows a schematic view of the magnetic probe rod system of thepresent invention which uses a permanent magnet as magnetic field sourceand has not a magnetically permeable material section at distal end.

FIG. 15 shows a diagram of the principle of interaction between magneticparticles and stones.

FIG. 16 shows a diagram of agitation of the reaction system in steps2-4) of the method for preparing the nanoparticles of the presentinvention, which uses a magnetic stirrer at a speed of 100-1000revolutions/minute, preferably 500-700 revolutions/minute.

FIG. 17 shows a diagram of the steps 1-4) of the method for preparingthe nanoparticles according to the present invention, in which aqueousammonia and liquid monomer are added dropwise continuously and uniformlyby an electronic pump at a rate of 20-100 drops/minute, preferably 40-60drops/minute.

FIG. 18 shows a diagram of comparison of stone removal performance forthe different methods.

FIG. 19 shows a diagram of in vivo stone removal performance for twomimic situations.

SPECIFIC MODELS FOR CARRYING OUT THE INVENTION

The present invention is further illustrated below with reference to theaccompanying drawings and specific examples. It should be understoodthat the following examples are only used to illustrate the presentinvention, rather than to limit the scope of the present invention.

According to a first aspect of the present invention, there is provideda use of a magnetic material for removal of stones, and further a use ofa magnetic nano-material for removal of stones. Meanwhile, the presentinvention provides a magnetic nano-material capable of safely andefficiently removing stones in urinary system, in which the magneticnano-material is a functional magnetic nanoparticle comprising, forexample, hydrophilic, hydrophobic, photosensitive, thermosensitive,pH-sensitive magnetic nanoparticles, which morphology can be spherical,rod-shaped and the like, which structure can be of core-shell structureconsisting of a magnetic core and a monomer modifier such ashydrophilic, hydrophobic, temperature sensitive, pH-sensitive orphotosensitive surface modifiers as well as a small amount of initiator;in which the hydrophilic surface modifier forms a hydrophilic shell bypolymerization to surround the magnetic nanoparticle core, including thehydrophilic materials with positive charges, negative charges andelectricity neutrality; the hydrophobic surface modification is carriedout by a poor water-soluble polymer or inorganic material; the otherfunctional materials such as photosensitive, thermosensitive andpH-sensitive monomer modifiers may be polymerized by a crosslinkingagent and embedded in a hydrophobic shell, or these monomer modifiersmay be in situ and directly attached to the surface of the core by aninitiator and/or crosslinking agent.

Among the various kinds of responsive magnetic nanoparticles such ashydrophilic, hydrophobic, thermosensitive, pH-sensitive andphotosensitive magnetic nanoparticles, the materials for synthesizingmagnetic nanoparticle cores comprise Fe³⁺, Fe²⁺ and Mn²⁺, Ni²⁺compounds, as well as metal elements such as iron (Fe), nickel (Ni),copper (Cu), cobalt (Co), platinum (Pt), gold (Au), europium (Eu),gadolinium (Gd), dysprosium (Dy), terbium (Tb), or composites and oxidesof the metals, such as Fe₃O₄ or MnFe₂O₄, preferably iron, manganese ortheir compounds; also preferably, any one of them or any combination oftwo or more of them may be used; and the core has a size of 2-50 nm.

The preparation method of the magnetic nanoparticle core includesco-precipitation methods, emulsion methods, redox reaction orhigh-temperature high-pressure methods. The weight percentage of themagnetic nanoparticle core accounts for 30% to 95% relative to the totalweight of the functional magnetic nanoparticle, taking the synthesis ofFe₃O₄ as example, the ratio of Fe²⁺ to Fe²⁺ is 15% to 85%, preferably1:2.5 to 1.5:1 for Fe³⁺ and Fe²⁺.

The surface of the magnetic nanoparticle can be subjected to functionalmodification, such as hydrophilic modification, hydrophobicmodification, and modification with photosensitive, thermosensitive andpH-sensitive materials.

According to a first embodiment of the present invention, there isprovided a hydrophilically modified functional particle, wherein thecore size is 2-50 nm, the magnetic nano-core has a weight of 30-95%relative to the total nanoparticle; the hydrophilic surface modifier isa polycationic or an anionic polymer, such as acrylic acid, methacrylicacid and isobutyl acrylamide, etc., which weight percentage is 2-8%relative to the whole phydrophobic magnetic nanoparticle. The magneticcore particle is attached on its surface with an initiator such as3-chloropropionic acid or the like, then a polymer based on acrylicacid, methacrylic acid and isobutyl acrylamide or the like is modifiedon the particle surface with a crosslinking agent by a chemicalreaction, such as radical, ring-opening polymerization and atom transferradical polymerization (ATRP); the shape of the particle may bespherical, rod-shaped and layered, preferably spherical particles. Thecrosslinking agent is 3-(methacryloyloxy) propyltriethoxysilane (MPS),divinylbenzene and diisocyanate or N,N-methylenebisacrylamide (MBA) andthe like.

According to a second embodiment of the present invention, there isprovided a hydrophobically modified functional particle, wherein thecore has a size of 2-50 nm, the magnetic nano-core is 30-95% by weightrelative to the whole nanoparticle; the hydrophobic surface modifier isan water insoluble monomer, such as olefins, for example, polystyreneand the like, which weight percentage is 2-8% by weight relative to thewhole hydrophobic magnetic nanoparticle. The magnetic core particle isattached to its surface with an initiator such as 3-chloropropionicacid, and then a hydrophobic polymer based on styrenes is modified onthe particle surface by a crosslinking agent via a chemical reactionsuch as radical, ring-opening polymerization and atom transfer radicalpolymerization (ATRP); the morphology of the particle may be spherical,rod-shaped and layered, preferably spherical particle. The crosslinkingagent is 3-(methacryloyloxy) propyl triethoxysilane (MPS),divinylbenzene and diisocyanate or N,N-methylenebisacrylamide (MBA) andthe like.

According to a third embodiment of the present invention, there isprovided a photosensitive surface-modified functional particle, whereinthe core has a size of 2-50 nm, and the magnetic core is 30-95% byweight relative to the whole nanoparticle; the photosensitive modifieris selected from the group consisting of azos and quinolines as well asbenzophenones (PVBP), etc., which weight percentage is 2-8% relative tothe whole hydrophobic magnetic nanoparticle. The magnetic core particleis attached to its surface with an initiator such as 3-chloropropionicacid, and then a photosensitive polymer based on benzophenone (PVBP) andthe like is modified to the surface of the particle by a crosslinkingagent via a chemical reaction such as radical, ring-openingpolymerization and atom transfer radical polymerization (ATRP); themorphology of the particle may be spherical, rod-shaped and layered,preferably spherical particle. The crosslinking agent is3-(methacryloyloxy) propyltriethoxysilane (MPS), divinylbenzene anddiisocyanate or N,N-methylenebisacrylamide (MBA) and the like.

According to a fourth embodiment of the present invention, there isprovided a thermosensitive surface-modified functional particle, whereinthe size of the core is 2-50 nm, and the magnetic nano-core is 30-95% byweight relative to the whole nanoparticle; the thermosensitive surfacemodifier is selected from the group consisting of amphiphilic polymerscarrying amide bonds, such as polyacrylamide, poly N-substitutedisopropylacrylamide, etc., which weight percentage is 2-8% relative tothe whole hydrophobic magnetic nanoparticle. The magnetic core particleis attached to its surface with an initiator such as 3-chloropropionicacid, and then a thermosensitive polymer such as poly N-substitutedisopropylacrylamide is modified to the surface of the particle by acrosslinking agent via a chemical reaction such as radical, ring-openingassembly and atom transfer radical polymerization (ATRP); the shape ofthe particle may be spherical, rod-shaped and layered, preferablyspherical particle. The crosslinking agent is 3-(methacryloyloxy)propyltriethoxysilane (MPS), divinylbenzene and diisocyanate orN,N-methylenebisacrylamide (MBA) and the like.

According to a fifth embodiment of the present invention, there isprovided a pH-sensitive surface-modified functional particle, whereinthe core has a diameter of 2 to 50 nm, the magnetic nano-core is 30 to95% by weight relative to the whole nanoparticle; the pH-sensitivesurface modifier is selected from the group consisting of polymerscarrying carboxyl groups and quaternary ammonium salt groups, such aspolyacrylic acid, dimethylaminoethyl ester and dimethylaminopropylmethacrylate, etc., which weight percentage is 2-8% relative to thewhole hydrophobic magnetic nanoparticle. The magnetic core particle isattached to its surface with an initiator such as 3-chloropropionicacid, and then a pH-sensitive polymer based on dimethylaminoethylmethacrylate and dimethylaminopropyl methacrylate or the like ismodified to the surface of the particle by a crosslinking agent via achemical reaction such as radical, ring-opening polymerization and atomtransfer radical polymerization (ATRP); the shape of the particle may bespherical, rod-shaped and layered, preferably spherical particle. Thecrosslinking agent is 3-(methacryloyloxy) propyltriethoxysilane (MPS),divinylbenzene and diisocyanate or N,N-methylenebisacrylamide (MBA) andthe like.

In the above embodiments of the present invention, an initiator and/or acrosslinking agent are further included. The initiator includes thermalinitiators, for example, potassium persulfate, ammonium persulfate andazo type initiators; the crosslinking agent includes 3-(methacryloyloxy)propyltriethoxysilane (MPS), divinylbenzene and diisocyanate orN,N-methylenebisacrylamide (MBA), molecular weight is 100,000, and oleicacid, etc.

According to a second aspect of the present invention, there is provideda preparation method for a nanoparticle obtained from a magneticmaterial. The preparation method generally includes two main steps:synthesis of a magnetic nanoparticle core (the magnetic materialconstitutes the nanoparticle core), and various surface modificationsbased on the magnetic nanoparticle core (hydrophilic, hydrophobic andthermosensitive, photosensitive and pH-sensitive modification). Takingthe preparation of magnetic Fe₃O₄ nanoparticles as an example, the twosteps of the preparation method are respectively described in detail.

1) Preparation of Magnetic Fe₃O₄ Nanoparticle Core

FeCl₃.6H₂O and FeCl₂.4H₂O in a certain molar ratio (the molar ratio ofFeCl₃.6H₂O and FeCl₂.4H₂O is 15% to 85%, preferably 1:2.5 to 1.5:1) aredissolved in 100 mL of water, fed with nitrogen gas to expel oxygen inthe solution, added with aqueous ammonia at a room temperature of 20-30°C. to adjust the pH value of 8-12, preferably 10, and kept agitation andreaction for 20-40 minutes; then under a 50-100 , preferably 70 waterbath, the reaction is carried out for 20-40 minutes, and then Fe₃O₄nanoparticles are obtained by separation with a magnet and drying. Thereare different kinds of preparation methods such as co-precipitationmethod, thermal decomposition method, hydrothermal synthesis method,microemulsion method (reverse micelle method) and the like.

2) Surface Modification of the Synthesized Fe₃O₄ Nanoparticle Core

2.1) Hydrophobic Modification of the Surface of the Synthesized Fe₃O₄Nanoparticle Core

The Fe₃O₄ nanoparticle core prepared in the step 1) is dispersed into anaqueous solution, added with an initiator 3-chloropropionic acid andpre-treated for 12 hours, then added with an xylene solution of ahydrophobic surface-modifying monomer polystyrene and an activeinitiator CuCl and 4,4′-dinonyl-2,2-dipyridine (the molar ratio of theiron particle solution and the reaction solution is 1:1), and themixture solution is reacted under continuous agitation at 130° C. for15-30 hours, preferably 24 hours; the resulting nanoparticles arecollected with a magnet and washed repeatedly with toluene to obtain thehydrophobic polystyrene-coated magnetic iron oxide nanoparticles.

Here, 3-chloropropionic acid is used as an initiator, and CuCl and4,4′-dinonyl-2,2-bipyridine are used as another initiator. In addition,according to one embodiment of the present invention, the reaction timeis preferably 18 to 30 hours, preferably 24 hours. In addition,according to one embodiment of the present invention, the solvent istoluene or xylene in an amount of ½ to 1 of the monomer volume, the massratio of the surface-modified polystyrene magnetic nanoparticles, theinitiator and the monomer is 95:0.5:4.5.

2.2) Hydrophilic Modification of the Surface of the Synthesized Fe₃O₄Nanoparticle Core

The Fe₃O₄ nanoparticle core obtained in the above step 1) is dissolvedand dispersed into xylene, added with a silane coupling agent (theaddition ratio of Fe₃O₄ nanoparticles and the silane coupling agent is95:5), and reacted at 80° C. under nitrogen protection for 2-5 hours,preferably 3 hours; then washed with an alcoholic solvent (preferablyabsolute ethanol) and dried for 12 h, dispersed in an aqueous solutionunder ultrasonic condition, added with potassium persulfate; reactedunder nitrogen protection at 40-80° C. for 10 minutes, then added withacrylic acid and reacted continuously at 40-80° C. for 1 hour,preferably reacted at a reaction temperature of 70° C.; separated by amagnet, washed and dried to obtain polyacrylic acid-modified,hydrophilic surface-modified magnetic nanoparticles.

Here, the silane coupling agent is 3-(methacryloyloxy)propyltriethoxysilane (MPS) in an amount of 8 to 16 times the mass of acrylicacid; the solvent is benzene or 2-toluene; potassium persulfate is usedas initiator; the reaction time is preferably 20 minutes to 80 minutes.According to one embodiment of the present invention, the mass ratio ofthe surface-modified magnetic Fe₃O₄ nanoparticles, the potassiumpersulfate and the acrylic acid monomer is 25-100:1:100.

In addition, the alcoholic solvent here is methanol, ethanol or butanol,preferably ethanol, the reaction temperature is preferably 100° C. to150° C., the reaction time is preferably 18 hours to 24 hours, and themass ratio of the photosensitive monomer-modified magneticnanoparticles, the potassium sulfate and the vinylbenzophenone monomeris 25-100:1:100.

2.3) Functional Modification of the Surface of the Synthesized Fe₃O₄Nanoparticle Core

The Fe₃O₄ nanoparticle core as prepared in the above step 1) isdissolved and dispersed into xylene, added with a silane coupling agent(the addition ratio of the Fe₃O₄ nanoparticles and the silane couplingagent is 95:5), reacted under nitrogen protection at 80° C. for 2-5hours, preferably 3 hours, then washed with an alcoholic solvent(preferably absolute ethanol) and dried for 12 hours, dispersed into anaqueous solution under ultrasonic condition, added with potassiumpersulfate; reacted under nitrogen protection at 40-80° C. for 10minutes, then added with a photosensitive monomer vinyl benzophenone, ora thermosensitive monomer N-substituted isopropylacrylamide, or apH-sensitive monomer dimethylaminoethyl methacrylate, reacted at 40-80°C. for 1 hour, preferably reacted at a reaction temperature of 70° C.;separated by a magnet, washed and dried to obtain magnetic nanoparticleswith photosensitive, thermosensitive or pH-sensitive surfacemodification, respectively.

In addition, the functionally modified nanoparticles here may also beobtained by a cross-reaction with steps 2.1 and 2.2) and step 3) afterpre-modification of the surface of the nanoparticle in the steps 2.1 and2.2). That is, after the modification of 3-chloropropionic acid in step2.1 (or the modification of silane coupling agent in step 2.2), thehydrophobic monomer styrene (or hydrophilic monomer acrylic acid) andthe functional monomer such as vinyl benzophenone, N-substitutedisopropylacrylamide or dimethylaminoethyl methacrylate and the like areadded at the same time, and reacted at 40-80° C. for 1 hour, preferablyreacted at a reaction temperature of 70° C.; separated by a magnet,washed and dried to obtain magnetic nanoparticles with photosensitive,thermosensitive or pH-sensitive surface modification. The co-reactionwould result in co-modified functional nanoparticles corresponding topolystyrene (or polyacrylic acid) and the functional monomer.

Here, the silane coupling agent is 3-(methacryloyloxy)propyltriethoxysilane (MPS) in an amount of 8 to 16 times the mass of acrylicacid; the solvent is benzene or 2-toluele in an amount of 8 to 16 timesthe mass of acrylic acid; potassium persulfate is used as initiator; thereaction time is preferably 20 minutes to 80 minutes. According to oneembodiment of the present invention, the mass ratio of thesurface-modified magnetic Fe₃O₄ nanoparticles, the potassium persulfateand the acrylic acid monomer is 25-100:1:100.

In addition, the alcoholic solvent here is methanol, ethanol or butanol,preferably ethanol, the reaction temperature is preferably 100° C. to150° C., and the reaction time is preferably 18 hours to 24 hours. Themass ratio of the functional monomer-modified magnetic nanoparticles,the potassium persulfate and the functional monomer is 25-100:1:100.

In the process for preparing the nano iron oxide (in step 1), the Fe₃O₄nanoparticles are nanoscale ferroferric oxide particles (Fe₃O₄),MnFe₂O₄, nanoscale ferric oxide particles (γ-Fe₂O₃) or other nanoscaleferrite particles, the aqueous ammonia is used as catalyst, the reactionpH is preferably 9 to 10, the reaction time is preferably 20 to 30minutes, the reaction temperature is between 50-100° C., preferably70-80° C., the preferred ratio of Fe³⁺:Fe²⁺ is 15% to 85%, preferably1.5:1 to 1:2.5.

In addition, in the above process for preparing nanoscale iron oxide(i.e., step 1)), the nanoparticle core is nanoscale ferroferric oxideparticles (Fe₃O₄). Those skilled in the art can understand that it isalso possible to use MnFe₂O₄, nanoscale ferric oxide particles (γ-Fe₂O₃)or other nanoscale ferrite particles. The aqueous ammonia is used ascatalyst, the reaction pH is preferably 9 to 10, the reaction time ispreferably 20-30 minutes, the reaction temperature is between 50-100°C., preferably 70-80° C. The preferred ratio of Fe³⁺:Fe²⁺ is 15% to 85%,preferably 1:2.5 to 1.5:1.

In addition, in the above embodiments of the present invention, theagitation in the above reaction system is performed by a magneticstirrer at a speed of 100-1000 revolutions/minute, preferably 500-700revolutions/minute.

In addition, in the above embodiments of the present invention, theaqueous ammonia and the liquid monomer are added dropwise continuouslyand uniformly by an electronic pump at a rate of 20-100 drops/minute,preferably 40-60 drops/minute. Through the use of electronic pump forcontinuous and uniform dripping, large-scale production can be easilyachieved, and the dispersibility and uniformity of nanoparticles can bewell controlled.

According to a third aspect of the present invention, there is provideda magnetic probe rod system for assisting the removal of stone inurinary system. The magnetic probe rod system comprises a handle 1, aflexible rod 2, a magnetic field source 3 and a magnetically permeablematerial section 4 (in the present invention, the side of the handle isdefined as the proximal end of the instrument, and the end of themagnetic field source is defined as the distal end). When anelectromagnet is selected as the magnetic field source 3, a switch 11can be integrated into the handle 1, and the magnetic field power supplycan be selected from DC battery, and a battery compartment 12 a and abattery cover 13 a are provided accordingly; when an AC power isselected as the magnetic field power supply, an AC power plug 12 b isprovided on the handle correspondingly. When the magnetic field sourceis an electromagnet, the magnetic field source 3 is composed of anelectromagnet core 32 a and an electromagnetic coil 33 a, and externallyprovided with a magnetic field source encapsulation membrane 31 a madeby biocompatible material; when the magnetic field source 3 is apermanent magnet, the magnetic field source 3 is composed of thepermanent magnet 32 b and the magnetic field source encapsulationmembrane 31 b on its surface; in order to ensure the accessibility ofthe present invention in human body, a magnetically permeable materialsection 4 can be optionally disposed at the distal end of the magneticfield source 3, that is, when the electromagnet is used as the magneticfield source, the magnetically permeable material section 4 a can beoptionally disposed at the distal end of the electromagnet 3 a, and themagnetically permeable material section is composed of a highlymagnetically permeable material 42 a and a magnetically permeablematerial encapsulating membrane 41 a, in which the highly magneticallypermeable material 42 a can be made of an iron-based magneticallypermeable material, preferably a pure iron material, and themagnetically permeable material encapsulating membrane 41 a and themagnetic field source encapsulation membrane 31 a can be made of thesame material; when the permanent magnet is selected as the magneticfield source, the magnetically permeable material section 4 b may alsobe disposed at the distal end of the permanent magnet 3 b, composed ofthe highly permeable material 42 b and the magnetically permeablematerial encapsulation membrane 41 b, and the magnetically permeablematerial encapsulation membrane 41 b and the magnetic field sourceencapsulation membrane 31 b can be made of the same material; when it isnot necessary to dispose a magnetically permeable material section atthe distal end of the magnetic field source, the system of the presentinvention is composed of the handle 1, the flexible rod 2 and themagnetic field source 3; for example, when the permanent magnet isselected as the magnetic field source, the magnetic field source atdistal end would be composed of a permanent magnet 32 c and anexternally disposed magnetic field source encapsulation membrane 31 c;in the above embodiment, the flexible rod 2 may be made of a polymermaterial such as PU, TPU, PE, PVC, NYLON, PEBAX and silicone rubber, aswell as modified materials of the above materials, and the magneticfield source encapsulation membranes 31 a, 31 b and 31 c as well as themagnetically permeable material encapsulation membranes 41 a and 41 bare all made of the same material as the flexible rods.

Further, the present invention provides a use of a magnetic nanoparticlein manufacture of an article, in which the magnetic nanoparticle isfurther processed to form a stone-removing solution (using physiologicalsaline, buffer as solvent) or a stone-removing powder, preferably astone-removing solution, which is used as a medical clinical article.

The basic principle of the high performance system for removing a stonein urinary system, which consists of the functional magneticnanoparticle composed of the magnetic material and the magnetic proberod as shown, is achieved by the following steps; 1) pulverization ofstones in vivo; 2) injection of the functional magnetic nanoparticles,the magnetic nanoparticles having excellent dispersibility(dispersibility and dispersion coefficient are related, the smaller thedispersion coefficient, the better the dispersibility); 3) interactionbetween the functional magnetic nanoparticles and the stones; 4)surrounding the stones with the functional magnetic nanoparticles: 5)physical or chemical crosslinking of the magnetic nanoparticles on thesurface of the stones; 6) removal of the magnetized stones under theguidance of an external magnetic field. Among them, the stones aresurrounded and magnetized by the magnetic nanoparticles via physicaladsorption, chemical bonding and the like. The physical adsorptionmainly refers to an attraction generated by van der Waal's force andhydrophobic interaction within the range of action between hydrophobicmagnetic particles—particles and between particles—stones, so that thesurface of the stones are adsorbed and surrounded by the magneticparticles; the chemical bonding mainly refers to the interaction betweenthe hydrophilic magnetic nanoparticles—particles and betweenparticles—stones mainly through the formation of chemical bonds(chemical bonds, such as hydrogen bonds, covalent bonds, etc., betweencarboxyl on the surface of the particles and the stones), so that thesurface of the stones is surrounded with the magnetic particles; thechemical bonding includes: the functional magnetic nanoparticles (suchas photosensitive, thermosensitive nanoparticles, etc.) firstly act onthe stones via physical adsorption, and then further enhance the mutualforces between particles—particles and particles—stones viaphotosensitive crosslinking, thermosensitive physical entanglement(crosslinking) and the like to surround the stones. The principle of theabove interaction is shown in FIG. 15:

The followings are detailed examples of the structure, preparation anduse of the magnetic nanoparticles of the present invention.

EXAMPLE 1 Preparation of Magnetic Nanoparticle Core

1. Preparation of 10 nm Fe₃O₄ By Co-Precipitation Method

3.05 g FeCl₃.6H₂O and 2.08 g FeCl₂.4H₂O (molar ratio 1:1) were dissolvedin 50 ml deionized water in a three-necked flask. Nitrogen gas was usedthroughout the experiment. Aqueous ammonia was added dropwise with asyringe and stirred vigorously at room temperature to adjust pH to 9,the solution gradually turned from yellow to brown and finally black,and the reaction was carried out for 20 minutes. After the reaction, thesolution was placed in a 70° C. water bath and incubated for 20 minutes,stirred vigorously to remove excess ammonia. The three-necked flask wastaken out and allowed to cool to room temperature under vigorousagitation. The suspension of the synthesized Fe₃O₄ magnetic particleswas poured into a 50 ml centrifuge tube, a powerful magnet was used toattract the magnetic particles, liquid waste was discarded, deionizedwater was added, the magnetic particles were re-suspended underultrasonic, so repeatedly to wash away excess ammonia until pH showedneutral. The collected magnetic particles were placed in an oven at 65°C. to be dried and dewatered. The synthesized magnetic particles wereweighed, and 1.0 ml suspension of 0.02 mg/ml magnetic particles wasformulated for measurement of particle size. A total of 1.5 ml of 0.02Msodium oleate solution was added dropwise to 1.0 ml suspension of 0.2mg/ml magnetic particles, reacted at 70□ under nitrogen and vigorousagitation for 30 minutes, and then cooled to room temperature. Excesssodium oleate was removed by dialysis using 12 KD dialysis membrane.Thus, 1.0 ml of 0.02 mg/ml sodium oleate-encapsulated Fe₃O₄ solution wasformulated, and its particle size was measured.

2. Preparation of Fe₃O₄ Magnetic Nanoparticle Core

2.1 Thermal Decomposition Method

2.1.1 Synthesis of 4 nm Fe₃O₄ Seeds:

5 mmol of ferric triacetylacetonate, 5 mmol of 1,2-dihydroxyhexadecane,3 mmol of oleic acid, 1 mmol of oleylamine were dissolved in 20 ml ofdiphenyl ether and magnetically stirred under a nitrogen atmosphere. Theabove mixture was stirred at 200° C. for 30 minutes, and then heatedunder reflux for 30 minutes at 265° C. under the protection of nitrogengas. The heating was stopped, and the dark brown liquid mixture obtainedfrom the reaction was cooled to room temperature; under atmosphericconditions, 400 ml of ethanol was added, and the resulting blackmaterial was separated by overspeed centrifugation. The black productobtained by centrifugation was redissolved in n-hexane containing 50 μLof oleic acid and 50 μL of oleylamine, centrifuged at 600 rpm for 10minutes to remove insoluble residues. The resulting 4 nm Fe₃O₄ productwas precipitated with ethanol, centrifuged at 600 rpm for 10 minutes toremove solvent and then redispersed into n-hexane. The followingdifferent methods were used respectively to synthesizesurface-functionalized nanoparticles with different sizes.

2.1.2 Synthesis of 6 nm Fe₃O₄ Nanoparticle Core Using 4 nm Fe₃O₄ Seeds

20 mmol of ferric triacetylacetonate, 10 mmol of1,2-dihydroxyhexadecane, 6 mmol of oleic acid and 6 mmol of oleylaminewere dissolved in 20 ml of diphenyl ether and magnetically stirred undera nitrogen atmosphere. The above mixture was heated at 200° C. for 2hours, and then heated under reflux for 1 h at 300° C. under theprotection of nitrogen gas. The heating was stopped, and the dark brownliquid mixture obtained from the reaction was cooled to roomtemperature. The aforementioned operation steps for the synthesis of the4 nm Fe₃O₄ particles were adopted to obtain a black brown suspension of6 nm Fe₃O₄ particles dispersed in n-hexane.

2.1.3 Synthesis of 8 nm Fe₃O₄ Nanoparticle Core using 6 m Fe₃O₄ Seeds

2 mmol of ferric triacetylacetonate, 10 mmol of 1,2-dihydroxyhexadecane,2 mmol of oleic acid and 2 mmol of oleylamine were dissolved in 20 ml ofethyl ether and magnetically stirred under nitrogen protection. 84 mg of6 nm Fe₃O₄ particles were weighed, dissolved in 4 ml of n-hexane, andthen added to the above mixture liquid. The above mixture liquid wasfirst heated at 100° C. for 30 minutes to remove n-hexane, then heatedat 200° C. for 1 hour, and heated under reflux at 300° C. for 30 minutesunder nitrogen protection. The heating was stopped, and the blackmixture liquid resulting from the reaction was allowed to cool to roomtemperature. The aforementioned synthesis steps for 4 nm Fe₃O₄ particleswas used to give a dark brown suspension of 8 nm Fe₃O₄ particlesdispersed in n-hexane. Similarly, 80 mg of 8 nm Fe₃O₄ seeds reacted with2 mmol of ferric triacetylacetonate and 10 mmol of1,2-dihydroxyhexadecane to produce 10 nm Fe₃O₄ nanoparticles. Using thisFe₃O₄ seed-mediated growth method, Fe₃O₄ nanoparticles with larger size(up to 20 nm) could be synthesized.

2.1.4. Surface Modification of Fe₃O₄ Nanoparticle Core

Under atmospheric conditions, 200 μl of n-hexane solvent with 20 mg ofdispersed hydrophobic Fe₃O₄ nanoparticle core was added to 2 ml ofdichloromethane suspension containing 20 mg of tetramethylammonium saltof 11-aminoundecanoic acid. The mixture was shaken for 20 minutes, whilea magnet was used to separate the precipitated Fe₃O₄ nanoparticles. Thesolvent and the non-magnetic suspended matter were decanted, theresulting precipitate was washed once with dichloromethane, and then theseparation with magnet was performed again to remove excess surfactant.The resulting product was dried under nitrogen gas and then dispersed indeionized water or pH-neutral PBS.

2.2 Hydrothermal Synthesis Method

1.35 g (5 mmol) of ferric chloride hexahydrate (FeCl₃.6H₂O) wasdissolved in 40 mL of ethylene glycol to form a clear solution. To theabove solution, 3.6 g of sodium acetate and 1.0 g of polyethylene glycolwere added, stirred vigorously for 30 minutes, and then transferred to a50 ml sealed stainless steel autoclave, reacted at 200° C. for 8-72hours, and then cooled to room temperature. The black product obtainedin the reaction was washed with ethanol for several times and then driedat 60° C. for 6 hours, to obtain a magnetic nanoparticle core having aparticle diameter of 10 nm or less.

2.3 Microemulsion Method (Reverse Micellar Method)

5 mmol of Mn(NO₃)₃ and 10 mmol of Fe(NO₃)₃ were dissolved in 25 mL ofdeionized water to form a clear and transparent solution: 25 mL of 0.4 MNaDBS ([CH₃(CH₂)₁₁(C₆H₄)SO₃]Na) was added to the above iron ionsolution, and then added with a large volume of toluene, in which thesize of the resulting MnFe₂O₄ nanoparticles particles depended on thevolume ratio of water and toluene. For example, in order to obtain 8 nmnanoparticles, the volume ratio of water and toluene should be 5:100.After the above mixture liquid was stirred overnight, it became a clearsingle-phase solution containing reversed micelles.

In order to form colloids in the reversed micelles, 40 mL of 1 M NaOHsolution was added dropwise with vigorous stirring, and the stirring wascontinued for 2 hours. The water and most of the toluene in the solutionwere removed by distillation to reduce the volume of the solution. Theresulting concentrated solution containing suspended colloids was washedwith water and ethanol to remove excess surfactant in the solution. Aprimary magnetic nanoparticle core was obtained by ultracentrifugation,and a nanocrystal was obtained by heating at 350° C. under nitrogenatmosphere for 12 hours.

EXAMPLE 2 Hydrophobic Polystyrene Surface Modification

(Modification on the Magnetic Nanoparticle Core (MnFe₂O₄) Obtained inExample 1)

MnFe₂O₄ nanoparticles with an average particle size of 9 nm were addedto an aqueous solution/3-chloropropionic acid solution with aconcentration of 1.0 mol/L initiator, the solution was adjusted to pH of4 with hydrochloric acid, and stirred overnight. The nanoparticles werecollected with a magnet, washed with water for several times to removeexcess 3-chloropropionic acid. 0.22 g of dried nanoparticles were addedto 8 mL of polystyrene solution under continuous feeding of nitrogengas, followed by the addition of 4 mL of an xylene solution of 0.3 mmolof CuCl and 1.1 mmol of 4,4′-dinonyl-2.2-dipyridine. The above mixturereacted at 130° C. for 24 h under continuous agitation. Thenanoparticles were collected with a magnet and washed repeatedly withtoluene to obtain polystyrene-coated magnetic iron oxide nanoparticles.

EXAMPLE 3 Hydrophilic Polyacrylic Acid Modification

1 g of Fe₃O₄ obtained in Example 1 (for example, 10 nm Fe₃O₄ obtained byco-precipitation method) and 5 ml of a silane coupling agent(methacryloxypropyltrimethoxysilane, KH570) were mixed with 50 ml ofxylene in a reaction flask. Under nitrogen protection, the reaction wascarried out under stirring at 80° C. for 3 hours. After the reaction,the mixture was centrifuged and washed with ethanol three times toremove the silane coupling agent adsorbed on the surface of the Fe₃O₄and vacuum-dried for 12 hours. The above-mentioned silane couplingagent-activated Fe₃O₄, 40 mg of potassium persulfate and 30 ml ofdeionized water were added in a flask, reacted under nitrogen protectionand stirring at 40 for 10 minutes. Then, 4 ml of acrylic acid was slowlydropped into the flask, and reacted under nitrogen protection andstirring at 40° C. for 1 hour. The nanoparticles were magneticallyseparated, washed three times with deionized water and finally driedunder vacuum.

EXAMPLE 4 Photosensitive Functional Modification of Nanoparticles

1. Synthesis of Photosensitive Functional Monomer

The synthesis method of photosensitive monomer with photo-crosslinkingcharacteristics comprised: 4-vinylbenzophenone (4 VBP) and styrenemonomer were directly polymerized by atom transfer radicalpolymerization (ATRP) to obtain a photosensitivepolystyrene-polyvinylbenzophenone copolymer (PS-PVBP), wherein thespecific steps were as follows: in a dry Schlenk tube connected with areflux condenser, Cu(I)Br (0.695 mg, 4.8 umol), 4 VBP (1.0 g, 4.8 mmol),styrene (2 u, 20 umol) and 4-vinylbenzophenone (1 μL, 4.8 umol) wereadded, and the mixture was degassed for three times by means offreeze-pump-thaw circulation. Methyl bromopropionate (5.35 μL, 48 umol)was added to the above mixture at −78° C. under condition of nitrogenwith positive pressure, and the mixture was degassed again for threemore times by means of freeze-pump-thaw circulation. Polymerization wascarried out by heating the mixture to a temperature of 85° C. undernegative pressure, and the reaction was allowed to proceed for 4 hours.The above Schlenk tube was immersed in liquid nitrogen, and 10 ml ofdichloromethane was added to dissolve the polymer. The resultingsolution was precipitated twice with methanol (2×300 mL) to givePS_(x)-PVBP_(y) as a light yellow solid, wherein x: y˜(60% -90%), and apreferred composition was PS₇₅-PVBP₂₅. In the same way,PS₇₅-PVBP₂₅-PAA₁₀₀ could be obtained by adding hydrophilic monomeracrylic acid.

2. Preparation of Nanoparticles Surrounded with PhotosensitiveCross-Linked Micelles

(Polystyrene₇₅-co-polyvinylbenzophenone₂₅)-polyacrylic acid₁₀₀, namely(PS₇₅-co-PVBP₂₅)₁₁₅-b-PAA₁₀₀, was chosen as a polymer to form micellesin aqueous solution. 5 mg of (PS₇₅-co-PVBP₂₅)₁₁₅-b-PAA₁₀₀ and 10 mg ofFe₃O₄ obtained in Example 1 (for example, 10 nm Fe₃O₄ obtained byco-precipitation method) were dissolved in 10 ml of dimethylformamide(DMF) solution; and then double distilled water (0.1 ml/min) wasgradually added under vigorous stirring. When the volume of waterreached 60%, the resulting solution was added to a dialysis membranewith a molecular weight cut off of 12K-14K and dialyzed against waterfor 24 hour to remove DMF, and then the micellar solution wastransferred to a quartz tube and irradiated with a laser at differenttime periods (emission wavelength: 315-400 nm) to form a photosensitivemonomer-coated nanoparticle.

EXAMPLE 5 Thermosensitive Functional Modification of Nanoparticles

1 g of Fe₃O₄ obtained in Example 1 (for example, 10 nm Fe₃O₄ obtained byco-precipitation method) and 5 ml of a silane coupling agent(methacryloxypropyltrimethoxysilane, KH570) were mixed with 50 ml ofxylene in a reaction flask. Under nitrogen protection, the reaction wascarried out with stirring at 80° C. for 3 hours. After the completion ofthe reaction, the mixture was centrifuged and washed with ethanol threetimes to remove the silane coupling agent adsorbed on the surface of theFe₃O₄, and vacuum-dried for 12 hours. The above-mentioned silanecoupling agent-activated Fe₃O₄, 40 mg of potassium persulfate and 30 mlof deionized water were added in a flask, reacted under nitrogenprotection and stirring at 40 for 10 minutes. Then, 4 ml ofN-isopropylacrylamide aqueous solution was slowly dropped into theflask, and reacted under nitrogen protection and stirring at 40° C. for1 hour. The nanoparticles were magnetically separated, washed threetimes with deionized water and finally dried in vacuo.

EXAMPLE 6 pH-Sensitive Functional Modifications of Nanoparticles

1 g of Fe₃O₄ obtained in Example 1 (for example, 10 nm Fe₃O₄ obtained byco-precipitation method) and 5 ml of a silane coupling agent(methacryloxypropyltrimethoxysilane, KH570) were mixed with 50 ml ofxylene in a reaction flask, and reacted under nitrogen protection andstirring at 80° C. for 3 hours. After the completion of the reaction,the mixture was centrifuged and washed with ethanol three times toremove the silane coupling agent adsorbed on the surface of the Fe₃O₄,and dried in vacuo for 12 hours. The above-mentioned silane couplingagent-activated Fe₃O₄, 40 mg of potassium persulfate and 30 ml ofdeionized water were added in a flask, reacted under nitrogen protectionand stirring at 40 for 10 minutes. Then, 4 ml of dimethylaminoethylmethacrylate aqueous solution was slowly dropped into the flask, andreacted at 40° C. for 1 hour under stirring and nitrogen protection. Thenanoparticles were magnetically separated, washed three times withdeionized water and finally dried in vacuo.

EXAMPLE 7 Biocompatibility Evaluation

Cell Plating: 293 t cells in logarithmic growth phase were digested,counted after centrifugation, and plated on a 96-well plate with a celldensity of 5.0×10⁴/well. 100 μl of serum-containing medium was added toeach well. The surronding blank wells were each complemented with 100 μlof serum-containing medium. The plate was placed in a 7% CO₂, 37° C.cell incubator overnight. The hydrophilically modified magneticnanoparticles of Example 3 in an amount of 100 μl per well were added tothe cell wells and incubated with N87 cells, wherein the magneticnanoparticles obtained in Example 3 was used in concentrations of 0.1,0.2, 0.4, 0.8, 1.0 mg/ml respectively. After incubated at 37□ for 24hours, the cells were gently washed twice with culture medium, and thenthe cell viability was measured with a Cell Counting Kit-8 kit, in whichthe detection conditions were as follows: 10 μl of CCK-8 reagent perwell, incubate at 37□ for 2 hours, read the absorbance value at 450 nmwith BIO-TEK ELx800 automatic microplate reader, and calculate the cellviability. The results shown in FIG. 5, indicating the synthesizedhydrophilically modified magnetic nanoparticles had goodbiocompatibility and almost no toxicity in vivo, and giving preliminaryevidences of applicability for in vivo experiments.

EXAMPLE 8 Evaluation of In Vitro Stone Separation with Assistance ofNanoparticles

As shown in FIG. 6, a certain amount of stones were weighed, pulverizedwith a pestle into a powder (particle size 0.5-2 mm), poured into atransparent glass bottle, and PBS solution was added to obtain a stoneliquid. After being mixed uniformly, the hydrophilically modifiedmagnetic particles of Example 3 at a concentration of 1 mg/ml was usedas a separation liquid and added, and then gently shaken. After standingfor 5 minutes, separation was carried out with a magnet. Duringstanding, it was observed that the color of the mixture gradually faded,and after 5 minutes, it was observed that the black magnetic particleswere adsorbed on the surface of the stone. Under the guidance of themagnetic field, the stones with magnetic particles adsorbed on theirsurface moved toward the magnet.

Example 9 Evaluation of In Vivo Safety of Nanoparticles in Animals

As shown in FIG. 7, one 6-week-old nude rat and 3 mice wereintraperitoneal injected and tail vein injected, respectively. Thehydrophilically modified magnetic nanoparticles of Example 3 at aconcentration of 0.5 mg/ml and in an amount of 200 μL were used for theinjection for consecutive two days. The living conditions of the micewere observed periodically (such as one week, two weeks, etc.). Theresults showed that after intravenous injection of 200 μL of magneticnanoparticle solution, no obvious toxicity was found in the nude rat andthe mice within 1 week; and after intraperitoneal injection of particlesolution at the same concentration 3 times, it was found that the ratand the mice had good survival status within 3 months. This shows thatthe prepared magnetic nanoparticles have good biocompatibility, and suchpreliminary assessment shows they basically have no acute toxicity andchronic toxicity.

EXAMPLE 10 Using Magnetic Nanoparticles in Removal of Urinary Stones

In the treatment of disease of kidney stones, an ureteroscope was usedfor holmium laser lithotripsy. In the operation, after crushing processof kidney stones with holmium laser, 200 ml of the hydrophilic magneticnanoparticle solution of Example 3 according to the present inventionwas injected into the kidney through the working channel of theureteroscope, so that the hydrophilic magnetic nanoparticle solution wasthoroughly mixed with the stone debris. After about 3 minutes, thenanoparticles in the solution completely adhered to the surface of thestone debris, and magnetized the stone debris. The above-mentionedmagnetic probe rod system for removal of stones in urinary system, inwhich a NdFeB permanent magnet was used as the magnetic field source 3,was inserted into the kidney through the working channel of theureteroscope. Under the action of the magnetic field at the distal endof the magnetic probe rod system, the magnetized stone debris movedcloser to the distal end of the magnetic probe rod and attracted to themagnetic probe rod. Finally, the magnetic probe rod system filled withstones debris at its distal end together with the ureteroscope weredrawn from the body through the soft sheath of the ureteroscope. Afterthe stone debris were removed from the distal end of the magnetic proberod, the magnetic probe rod could be inserted again into the endoscopeto carry out stone removal operation, until all of the stone debrisinside the kidney were removed from the body. In this Example, the stonehad a diameter of about 20 mm and was located in the lower kidney calyx.By using the magnetic probe rod system in combination with thehydrophilic magnetic nanoparticle material of the present invention, all(100%) of the stone debris were removed from the body. In comparisonwith the traditional method of removing stones by baskets and the methodof pulverizing stones and then allowing patients to discharge stonedebris, the technical solutions of the present invention achievedsimple, efficient and complete removal of stones, thereby greatlyimproving the efficiency and safety of stone removal operations.

EXAMPLE 11 Comparison of Different Methods for Stone Extraction

Step 1. Synthesis of Magnetic Particles

From the left mouth of the three-mouth bottle, ferrous iron and ferriciron solutions were added, the total volume was 200 ml. The left mouthwas sealed with a glass stopper, the right mouth was sealed withnitrogen gas, and the mechanical stirrer was set at a speed of 500,timing for 30 min. After 30 min, aqueous ammonia was added dropwise witha syringe to adjust pH to 10.0; and timing for 30 min again; a waterbath at 80° C. was prepared, and the three-mouth bottle was transferredto the water bath, and the reaction was continued for 30 minutes. After30 minutes, the instrument was turned off and allowed to cool to roomtemperature. After being washed with deionized water twice, acetoneonce, the product was placed in an oven for drying.

Step 2. Screening

After being dried, the product was ground, and screened over mesh sievesinto three grades of magnetic particles: d≤0.048 mm, 0.048 mm≤d≤0.106mm, d≥0.106 mm,

Step 3. Surface Modification of Magnetic Particles

150 mg of magnetic particles was added in a three-necked flask intowhich a magnetic rotor was placed. When oil bath temperature waselevated to 80 degrees Celsius, 15 ml of xylene solution was added, fedwith nitrogen gas immediately and sealed, adjusting the rotation speed.After 10 minutes, 1.5 ml of silane was added, timing for 6 hours, and anitrogen pack was connected. After 6 hours, the three-necked flask wasremoved, the xylene was poured out, the product was washed with ethanoltwice, 10 minutes for each time, 20 ml for each dose, and then washedwith dd water twice. 15 ml of deionized water was prepared, the magneticparticles was transferred to the bottle, fed with nitrogen gas for 20minutes, adjusting the rotation speed at 3 and the oil bath temperatureof 70□. 20 mg of potassium persulfate dissolved in a solution at roomtemperature was added, continuously passing nitrogen gas for 10 minutes.1.5 ml of acrylic acid was added dropwise, the reaction in the flask wasobserved; adjusting rotation speed, and stopping the reaction after 20minutes. The product was washed with sodium hydroxide solution twice,transferred to a beaker, and then washed twice with deionized water;re-suspended in water.

In order to compare the stone removal performance of the lithotomy withmagnetic material (i.e., magnetic nanoparticles) of the presentapplication with the polymer gel stone removal method existing in theprior art, the inventor designed a stone basket, and a cationic polymerpolyethylenimine gel with gel composition according to CN105283140A wasused to simulate the gel in the kit.

Specifically, two glass bottles as shown in FIG. 18 were used, and eachof them was added with 3 pieces of 2-3 mm blank stones, the stones inthe bottle (a) were not modified, while the stones in the bottle (b)were treated with 1 ml (3 mg/ml) of the magnetic particle solution ofstep 3 for modification. After 5 minutes, the magnetic particle solutionwas sucked out from the bottle (b), and then the bottles (a) and (b)were added with 2 ml of physiological saline, respectively.

The experimental results show that the magnetic particles had stoneremoval effect (3 stones were removed) significantly superior to thepolymer gel stone removal method (0 stone was removed).

From Example 11, it can be seen that the magnetic nanoparticles asclaimed in the present invention have excellent effect in stone removalapplications relative to the gel stone removal method existing in theprior art (for example, CN105283140A).

EXAMPLE 12 Effects of Two Mimicking Experiments for Stone Removal InVivo

The purpose of this experiment was to simulate stone removal effectsgradually and really from simple to complex. Therefore, the experimentwas divided into two parts:

1. Using an Urethra Model with Two Calices Simulated with TransparentGlass Tube

Modification of stones: To simulate the in vivo environment, threestones with diameter of 2-3 mm were placed in the transparent glass tubefor simulating urethra model with two calices, which was the initialstate of the environment for the stone in kidney (see FIG. 19-1).

The whole chamber was filled with physiological saline, and 1 ml (3mg/ml) of the magnetic particle solution (the magnetic particlesobtained in Example 11) was injected through a microinjector catheter,timing for 5 min. The experimental results showed that when a magneticprobe was used to verify stone removal effect, the stone could be quickguided and removed successfully (see FIG. 19-2).

The results of the adsorption of stones on the magnetic probe were shownin FIG. 19-3.

2. Using a Transparent Artificial Kidney Model

Compared with the previous model, this model was basically the same instructure, size and shape as a human kidney, and had more complicatedstructure and pipeline obstructions. The purpose was to perform furtherin vitro simulation, and to observe the effects of obstructions possiblyexisting in kidney calices and urethra on stone removal.

Modification of stones: In order to better simulate the environment forstones in kidney, a glass model was made, and three stones with diameterof 2-3 mm were placed in the transparent artificial kidney model, whichwas the initial state of the environment for stones in kidney (see FIG.19-4).

The whole chamber was filled with physiological saline, and 1 ml (3mg/ml) of the magnetic particle solution (the magnetic particlesobtained in Example 11) was injected through a microinjector catheter,timing for 5 min. The experimental results showed that when a magneticprobe was used to verify stone removal effect, the obstructions incalices and pipeline basically had not effect on the removal of stone,and the stones were removed successfully (see FIG. 19-5).

The results of the adsorption of stones on the magnetic probe were shownin FIG. 19-6.

From Example 12, it can be seen that the magnetic nanoparticles of thepresent application have excellent effects in the two experiments thatsimulate the removal of stones in vivo, and furthermore, the magneticnanoparticles have a good application prospect in stone removalapplications.

While many embodiments of the invention have been shown and/or discussedherein, it is not intended that the invention is limited thereto. It isanticipated that the scope of the present invention will be the same aswhat is allowed in the art and interpreted from the description.Therefore, the above description should not be construed as limitation,but merely as exemplifications of specific embodiments. Those skilled inthe art can envision other variations within the scope and spirit ofClaims appended hereto.

What is claimed is:
 1. A method of the use of a magnetic material inremoval of a stone, wherein the magnetic material magnetizes the stoneby physical adsorption, chemical bonding or the like, and removes thestone by the action of a non-contact magnetic field.
 2. The methodaccording to claim 1, wherein the magnetic material comprises thefollowing components; a preparation containing a magnetic metal elementor a compound thereof; and materials capable of binding to calcium salt.3. The method according to claim 2, wherein the preparation containingthe magnetic metal element or compound thereof and the materials capableof binding to calcium salt form a structure that may be a clad structureor a core-shell structure, for example, the materials are completely orpartially covered on the surface of the preparation; or form a modifiedstructure in which the materials are bonded to the surface of thepreparation by absorption; or form a complex structure in which thepreparation and the materials form a physical mixture; or form acomposite structure of the aforementioned structures.
 4. The methodaccording to claim 2, wherein the preparation containing the magneticmetal element or compound thereof is in nano-scale or in micro-scale. 5.The method according to claim 2, wherein the materials capable ofbinding to calcium salt are surfactants or polymer compounds.
 6. Themethod according to claim 2, wherein the materials capable of binding tocalcium salt are macromolecular compounds.
 7. The method according toclaim 1, wherein the magnetic material includes carboxyl, amido, amino,mercapto, hydroxyl, carbonyl, ether group, amine group, ester group,carbamate group, carbamido or quaternary amine group, sulfonic acidgroup, sulfhydryl, phosphine group or conjugate acid or base thereof,epoxy group, chlorine group, sulfate group, phosphinic acid, sulfinicacid, carboxylic anhydride group, hydrosilyl group, amine group andmoiety of any combination thereof, aldehyde group, unsaturated doublebond, phosphoric acid group, halogen group, N-succinimido, maleimido,ethylenediaminetriacetic acid alkyl group, polyethylene glycol,polyamino acid or glycan, preferably carboxyl, amido, mercapto,carbamate group, carbamido, sulfonic acid group, phosphino conjugateacid, phosphino basic group, sulfate group, phosphinic acid, sulfinicacid, N-succinimido, maleimido, polyamino acid.
 8. The method accordingto claim 1, wherein the magnetic material is in the shape of bar, line,band, sheet, tube, pomegranate, cube, three-dimensional flower, petal,chestnut, four-pointed star, shuttle, rice grain, sea urchin, chainball, rugby ball, string of beads, snowflake, ellipsoid, sphere, regulartetrahedron, regular hexahedron, regular octahedron, quasi-sphere,popcorn, cross, strip, rod, cone, disc, branch, web, simple cubic,body-centered cubic, face-centered cubic, simple tetragon, body-centeredtetragon, simple orthogon, body-centered orthogon, single-face-centeredorthogon, multi-shell, laminar, preferably the shape of sphere,quasi-sphere, pomegranate, chestnut, sea urchin, chain ball, string ofbeads.
 9. The method according to claim 1, wherein the magnetic materialincludes a magnetic fluid, a magnetic liposome, a magnetic microcapsule,a magnetic microsphere, a magnetic emulsion, a magnetic nanoparticle, amagnetic nanotube, a magnetic nanowire, a magnetic nanorod, a magneticnanoribbons, preferably a magnetic fluid, a magnetic liposome, amagnetic microsphere, a magnetic nanotube.
 10. The method according toclaim 9, wherein the magnetic liposome includes a magnetic liposomewhich surface is modified to carry a functional group as described inclaim
 7. 11. The method according to claim 9, wherein the type of themagnetic liposome includes a single layer, a multi-layer, amulti-vesicle, and the preparation method of the magnetic liposomeincludes preferably a film dispersion method and an ultrasonicdispersion method.
 12. The method according to claim 9, wherein themagnetic fluid is a stable suspension liquid composed of magneticparticles, a carrier liquid (mineral oil, silicone oil, etc.) and asurfactant, the magnetic particles that can be method for removal ofstones comprise magnetic nanoparticles which surface is modified withthe functional group according to claim 7, and also comprise asurfactant with the functional group as described in claim
 7. 13. Themethod according to claim 9, wherein the preparation method for themagnetic fluid includes a chemical co-precipitation method, a sol-gelmethod, a hydrothermal synthesis method, a microemulsion method, a phasetransfer method, preferably a co-precipitation method, a sol-gel method,a hydrothermal synthesis method.
 14. The method according to claim 9,wherein the magnetic microsphere is characterized by a surface modifiedwith or covered with the functional group as described in claim
 7. 15.The method according to claim 9, wherein the preparation method for themagnetic microsphere includes an emulsion volatilization method, asolvent replacement method and a salting-out method.
 16. The methodaccording to claim 1, the magnetic nanotube comprises a magneticnanotube in which a magnetic material is filled in the tube and also amagnetic nanotube in which a magnetic material covers outside the tube,the surface of which has the functional group described in claim 7, andthe functional group may be derived from the magnetic material coveredon surface or from the nanotube itself.
 17. The method according toclaim 1, wherein the preparation method for the magnetic nanotubeincludes a chemical vapor deposition method, a co-precipitation method,a dip-pyrolysis method, an electroless plating method and aself-assembly method, and the preferred method is a co-precipitationmethod.
 18. The method according to claim 1, the magnetic nanoparticleis surface-modified or covered with the functional group as described inclaim
 7. 19. The method according to claim 1, wherein the magneticmaterial constitutes a nanoparticle core; and the nanoparticle core isin-situ modified with a surface modifier monomer by using an initiatorand/or a crosslinking agent to form a nanoparticle shell.
 20. The methodaccording to claim 19, wherein the nanoparticle core has a diameter of2-50 nm, and a weight percentage of 30-95% relative to the whole weightof the nanoparticle, and its magnetic material includes a compound ofFe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, or a metal element selected from iron, nickel,copper, cobalt, platinum, gold, europium, gadolinium, dysprosium,terbium, or a composite or oxide of the aforementioned metals, or anyone of the above items or a combination of two or more of the aboveitems, preferably a compound of Fe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, morepreferably Fe³⁺ and Fe²⁺ in a ratio of 15% to 85%, preferably 1:2.5 to1.5:1.
 21. The method according to claim 19, wherein the mutual forcesfor surrounding and crosslinking between the nanoparticle and stoneinclude van der Waals force, hydrophobic interaction, adsorption andsurface deposition that form surrounding interaction; a chemical bondformed between carboxyl-stone, including a hydrogen bond, an ester bond,an amide bond and other covalent bonds; physical and chemicalinter-chain entanglements between chains and chemical crosslinkingbetween chains.
 22. The method according to any one of claims 19-21,wherein the surface modifier includes a hydrophilic surface modifierwith function, response, a hydrophobic surface modifier with functionresponse, a photosensitive surface modifier with function response, athermosensitive surface modifier with function response or a pHsensitive surface modifier with function response, wherein thehydrophilic surface modifier includes acrylic acid, methacrylic acid,isobutyl acrylamide or poly N-substituted isopropylacrylamide; thehydrophobic surface modifier includes olefins, preferably polystyrene,polyethylene or oleic acid; the photosensitive surface modifier isselected from the group consisting of azos and quinolines andbenzophenones (PVBP), preferably ethylene benzophenone; thethermosensitive surface modifier is selected from amphiphilic polymerswith amide bond, preferably polyacrylamide or poly N-substitutedisopropylacrylamide; the pH-sensitive surface modifier is selected fromthe group consisting of polymers with carboxyl group and quaternaryammonium salt, preferably a polyacrylic acid, dimethylaminoethyl esterand dimethylaminopropyl methacrylate; the shell accounts for 2-40% byweight of the nano-particle, preferably the particle is of a shape ofsphere, rod or diamond.
 23. The method according to any one of claims 19to 21, wherein the crosslinking agent includes3-(methacryloyloxy)propyltriethoxysilane, divinylbenzene, diisocyanateor N,N-methylenebisacrylamide, and the initiator includes3-chloropropionic acid, CuCl, 4,4′-dinonyl-2,2-bipyridine or potassiumpersulfate.
 24. The method according to any one of claims 19-21, whereinthe preparation method for the nanoparticle includes the steps of: a)preparing the nanoparticle core using the magnetic material; b) formingthe nanoparticle by in situ linking the surface modifier monomer to thenanoparticle core by the initiator and/or crosslinking agent to form thenanoparticle shell.
 25. The method according to claim 24, wherein themagnetic material includes a compound of Fe³⁺, Fe²⁺, Mn²⁺ or Ni²⁺, or ametal element selected from iron, nickel, copper, cobalt, platinum,gold, europium, gadolinium, dysprosium, terbium, or a composite or oxideof the aforementioned metals, or any one of the above items or acombination of two or more of the above items, preferably Fe₃O₄,MnFe₂O₄, γ-Fe₂O₃ or other nanoscale-sized ferrite particles, morepreferably FeCl₃.6H₂O and FeCl₂.4H₂O in a molar ratio of 15% to 85%,preferably 1:2.5 to 1.5:1, and is prepared by the following steps:dissolving a proportion of the metal salt-containing material in water;feeding nitrogen to expel oxygen in the solution; adding a catalyst at aroom temperature of 10-40° C. preferably 30° C. to adjust the pH to7-12, preferably 10; keeping agitation for 10-60 minutes; and reactingunder condition of 40-100° C. preferably 70° C. water bath, for 20-40minutes, then separating with a magnet and drying to obtain the magneticnanoparticle core.
 26. The method according to claim 25, wherein whenaqueous ammonia is used as the catalyst for preparing the nanoparticle,the method for adding aqueous ammonia is a continuous dropping methodwith assistance of an electronic pump at a speed of 20-100 drops/minute,preferably 40-60 drops/minute; and when the magnetic material is aliquid monomer material, the liquid monomer is added drop wise incontinuous manner with assistance of an electronic pump, and thereaction agitation is at a speed of 100-1000 revolutions/minute,preferably 500-700 revolutions/minute.
 27. The method according to anyone of claims 25-26, wherein said method further includes performinghydrophobic surface modification on the obtained nanoparticle core,comprising the steps of: dispersing the prepared nanoparticle core in anaqueous solution and added with a xylene solution of 3-chloropropionicacid, polystyrene, CuCl and 4,4′-dinonyl-2,2-dipyridine, and the molarration between the above-mentioned nanoparticle core and the reactionsolution is 1:1; reacting the above mixture at 130° C. with continuousagitation for 15-30 h, preferably for 24 hours; and collecting thenanoparticle with a magnet and washing repeatedly with toluene to obtaina hydrophobic polystyrene-coated magnetic nanoparticle.
 28. The methodaccording to any one of claims 25-26, wherein said method furtherincludes performing hydrophilic surface modification on the obtainednanoparticle core comprising the steps of: dispersing the nanoparticlecore in xylene, and adding a silane coupling agent, wherein the ratio ofthe added nanoparticles, xylene and silane coupling agent is 95:5;reacting under protection of nitrogen atmosphere at a temperature of 20to 100° C., preferably 80° C. for 2 to 5 hours, preferably 3 hours;washing with an alcohol solvent and drying for 12 h, dispersing in anaqueous solution under ultrasonic condition, adding with potassiumpersulfate; reacting under protection of nitrogen atmosphere at 40-80°C. for 10 minutes, then adding with acrylic acid and continuouslyreacting at 40-80° C. for 1 hour, preferably reacting at 70° C.; andseparating by a magnet, washing and drying to prepare and obtain apolyacrylic acid-modified hydrophilic nanoparticle.
 29. The methodaccording to any one of claims 25-26, wherein said method furtherincludes performing a photosensitive, thermosensitive or pH-sensitivesurface modification based on the resulting nanoparticle core orhydrophilic surface, or a hydrophilic, hydrophobic, photosensitive,thermosensitive and pH-sensitive co-modification based on the resultingnanoparticle core, wherein the re-modification on the hydrophilicsurface includes the steps of: dissolving and dispersing the polyacrylicacid-modified magnetic nanoparticles in an alcoholic solvent, addingwith a photosensitive monomer such as ethylene benzophenone, athermosensitive monomer such as N-isopropylacrylamide, or a pH-sensitivemonomer such as dimethylaminopropyl methacrylate or a blend monomer ofacrylic acid and styrene, keeping reaction at 40-80° C. for 1 h,preferably at a reaction temperature of 70° C.; and separating with amagnet, washing and drying to obtain a photosensitive, thermosensitiveor pH sensitive functional monomer-modified magnetic nanoparticles,respectively.
 30. The method according to claim 1, wherein the stoneincludes urinary system, stones, such as kidney stones, ureteral stonesand bladder stones, human biliary system stones, and stone-likeparticles in other organs.
 31. The method according to claim 1, whereinthe interactions between the magnetic material and stone include ionicbonds, van der Waals forces that form surrounding interactions,hydrophobic interactions, adsorption and surface deposition; chemicalbonds between the carboxyl-stone, including hydrogen bonds, ester bonds,amide bonds and other covalent bonds; physical and chemical inter-chainentanglement between chains and chemical crosslinking between chains.